Schedule 13G/A: Janus Henderson Discloses 6.94M LNTH Shares (10%)

Rhea-AI Filing Summary

Janus Henderson Group plc filed an amended Schedule 13G reporting beneficial ownership in Lantheus Holdings, Inc. The filing lists an aggregate 6,938,984 shares, representing 10.0% of the class, with no sole voting or dispositive power and 6,938,984 shares held with shared voting and dispositive power.

The filing also identifies an indirect subsidiary, JHIUS, as potentially beneficially owning 6,242,218 shares (9.0%). The report includes issuer and filer addresses, a power of attorney executed Dec 9, 2022, and is signed by Kristin Mariani as Head of North America Compliance on 08/14/2025.

Positive

• Material institutional stake disclosed: 6,938,984 shares representing 10.0% of LNTH common stock
• Clear power attribution: shared voting and dispositive power specified for the full reported stake
• Subsidiary disclosure: JHIUS identified as beneficial owner of 6,242,218 shares (9.0%), improving transparency

Negative

• None.

Insights

Financial Analyst

TL;DR: Janus Henderson reports a material passive stake—10.0% (6.94M shares) in LNTH, disclosed under shared voting/dispositive power.

The Schedule 13G/A shows Janus Henderson Group plc as a reporting person with shared voting and dispositive control of 6,938,984 shares, equal to 10.0% of Lantheus common stock. The filing distinguishes subsidiary-level holdings (JHIUS at 6,242,218 shares, 9.0%). This is a standard regulatory disclosure of a large institutional position rather than an activist intent; no sole voting power is reported. The POA and timely signature indicate routine compliance processes.

Corporate Governance Expert

TL;DR: This disclosure documents significant institutional ownership and identifies control relationships among subsidiaries.

Janus Henderson Group plc is identified as the reporting entity (citizenship Jersey) and provides subsidiary attribution for JHIUS, JHIUKL and JHIAIFML. The filing shows shared voting/dispositive power for 6,938,984 shares and clarifies that holdings are held in the ordinary course of business. The document includes an executed power of attorney and a compliance officer signature, satisfying procedural filing requirements.

SECURITIES AND EXCHANGE COMMISSION
Washington, D.C. 20549

SCHEDULE 13G

UNDER THE SECURITIES EXCHANGE ACT OF 1934

(Amendment No. 4)

LANTHEUS HOLDINGS, INC.

(Name of Issuer)

Common Stock

(Title of Class of Securities)

516544103

(CUSIP Number)

06/30/2025

(Date of Event Which Requires Filing of this Statement)

Check the appropriate box to designate the rule pursuant to which this Schedule is filed:

Rule 13d-1(b)

Rule 13d-1(c)

Rule 13d-1(d)

SCHEDULE 13G

CUSIP No. 516544103

1

Names of Reporting Persons

JANUS HENDERSON GROUP PLC

2

Check the appropriate box if a member of a Group (see instructions)

(a)
(b)

3

Sec Use Only

4

Citizenship or Place of Organization

JERSEY

Number of Shares Beneficially Owned by Each Reporting Person With:

5	Sole Voting Power 0.00
6	Shared Voting Power 6,938,984.00
7	Sole Dispositive Power 0.00
8	Shared Dispositive Power 6,938,984.00

9

Aggregate Amount Beneficially Owned by Each Reporting Person

6,938,984.00

10

Check box if the aggregate amount in row (9) excludes certain shares (See Instructions)

11

Percent of class represented by amount in row (9)

10.0 %

12

Type of Reporting Person (See Instructions)

IA, HC

SCHEDULE 13G

Item 1.
(a)	Name of issuer: LANTHEUS HOLDINGS, INC.
(b)	Address of issuer's principal executive offices: 201 BURLINGTON ROAD, SOUTH BUILDING BEDFORD, MA 01730
Item 2.
(a)	Name of person filing: Janus Henderson Group plc
(b)	Address or principal business office or, if none, residence: 201 Bishopsgate EC2M 3AE, United Kingdom
(c)	Citizenship: Y9
(d)	Title of class of securities: Common Stock
(e)	CUSIP No.: 516544103
Item 3.	If this statement is filed pursuant to §§ 240.13d-1(b) or 240.13d-2(b) or (c), check whether the person filing is a:
(a)	Broker or dealer registered under section 15 of the Act (15 U.S.C. 78o);
(b)	Bank as defined in section 3(a)(6) of the Act (15 U.S.C. 78c);
(c)	Insurance company as defined in section 3(a)(19) of the Act (15 U.S.C. 78c);
(d)	Investment company registered under section 8 of the Investment Company Act of 1940 (15 U.S.C. 80a-8);
(e)	An investment adviser in accordance with § 240.13d-1(b)(1)(ii)(E);
(f)	An employee benefit plan or endowment fund in accordance with § 240.13d-1(b)(1)(ii)(F);
(g)	A parent holding company or control person in accordance with § 240.13d-1(b)(1)(ii)(G);
(h)	A savings associations as defined in Section 3(b) of the Federal Deposit Insurance Act (12 U.S.C. 1813);
(i)	A church plan that is excluded from the definition of an investment company under section 3(c)(14) of the Investment Company Act of 1940 (15 U.S.C. 80a-3);
(j)	A non-U.S. institution in accordance with § 240.13d-1(b)(1)(ii)(J). If filing as a non-U.S. institution in accordance with § 240.13d-1(b)(1)(ii)(J), please specify the type of institution:
(k)	Group, in accordance with Rule 240.13d-1(b)(1)(ii)(K).
Item 4.	Ownership
(a)	Amount beneficially owned: JHIUS may be deemed to be the beneficial owner of 6,242,218 shares
(b)	Percent of class: 9.0 %
(c)	Number of shares as to which the person has:
	(i) Sole power to vote or to direct the vote: 0
	(ii) Shared power to vote or to direct the vote: 6242218
	(iii) Sole power to dispose or to direct the disposition of: 0
	(iv) Shared power to dispose or to direct the disposition of: 6242218
Item 5.	Ownership of 5 Percent or Less of a Class.
Item 6.	Ownership of more than 5 Percent on Behalf of Another Person.
	If any other person is known to have the right to receive or the power to direct the receipt of dividends from, or the proceeds from the sale of, such securities, a statement to that effect should be included in response to this item and, if such interest relates to more than 5 percent of the class, such person should be identified. A listing of the shareholders of an investment company registered under the Investment Company Act of 1940 or the beneficiaries of employee benefit plan, pension fund or endowment fund is not required. N/A
Item 7.	Identification and Classification of the Subsidiary Which Acquired the Security Being Reported on by the Parent Holding Company or Control Person.
	If a parent holding company has filed this schedule, pursuant to Rule 13d-1(b)(ii)(G), so indicate under Item 3(g) and attach an exhibit stating the identity and the Item 3 classification of the relevant subsidiary. If a parent holding company has filed this schedule pursuant to Rule 13d-1(c) or Rule 13d-1(d), attach an exhibit stating the identification of the relevant subsidiary. JHIUS, JHIUKL and JHIAIFML are indirect subsidiaries of Janus Henderson and are registered investment advisers furnishing investment advice to Managed Portfolios.
Item 8.	Identification and Classification of Members of the Group.
	If a group has filed this schedule pursuant to §240.13d-1(b)(1)(ii)(J), so indicate under Item 3(j) and attach an exhibit stating the identity and Item 3 classification of each member of the group. If a group has filed this schedule pursuant to §240.13d-1(c) or §240.13d-1(d), attach an exhibit stating the identity of each member of the group. N/A
Item 9.	Notice of Dissolution of Group.
	Notice of dissolution of a group may be furnished as an exhibit stating the date of the dissolution and that all further filings with respect to transactions in the security reported on will be filed, if required, by members of the group, in their individual capacity. See Item 5. N/A

Item 10.

Certifications:

By signing below I certify that, to the best of my knowledge and belief, the securities referred to above were acquired and are held in the ordinary course of business and were not acquired and are not held for the purpose of or with the effect of changing or influencing the control of the issuer of the securities and were not acquired and are not held in connection with or as a participant in any transaction having that purpose or effect, other than activities solely in connection with a nomination under § 240.14a-11.

SIGNATURE

After reasonable inquiry and to the best of my knowledge and belief, I certify that the information set forth in this statement is true, complete and correct.

JANUS HENDERSON GROUP PLC

Signature:	Kristin Mariani
Name/Title:	Head of North America Compliance, CCO
Date:	08/14/2025

Exhibit Information

POWER OF ATTORNEY The undersigned, Janus Henderson Group plc ("the Company"), does hereby make, constitute and appoint each of Kristin Mariani and Caroline Barotti acting severally, as its true and lawful attorneys in-fact, for the purpose of, from time to time, executing in its name and on its behalf, whether the Company individually or as representative of others, any and all documents, certificates, instruments, statements, other filings and amendments to the foregoing (collectively, "documents") determined by such person to be necessary or appropriate to comply with ownership or control-person reporting requirements imposed by any United States or non-United States governmental or regulatory authority, including, without limitation, Forms 13D, 13F, 13G and 13H and any amendments to any of the foregoing as may be required to be filed with the Securities and Exchange Commission, and delivering, furnishing or filing any such documents with the appropriate governmental, regulatory authority or other person, and giving and granting to each such attorney-in-fact power and authority to act in the premises as fully and to all intents and purposes as the Company might or could do if personally present by one of its authorized signatories, hereby ratifying and confirming all that said attorney-in-fact shall lawfully do or cause to be done by virtue hereof. Any such determination by an attorney-in-fact named herein shall be conclusively evidenced by such person's execution, delivery, furnishing or filing of the applicable document. This power of attorney shall be valid from the date hereof and shall remain in full force and effect until either revoked in writing by the Company, or, in respect of any attorney-in-fact named herein, until such person ceases to be an employee of the Company or one of its affiliates. IN WITNESS WHEREOF, the undersigned has caused this power of attorney to be executed as of this 9th day of December, 2022. Janus Henderson Group plc By: /s/ Michelle Rosenberg Name: Michelle Rosenberg Title: General Counsel and Company Secretary

FAQ

What stake does Janus Henderson hold in Lantheus (LNTH)?

Janus Henderson Group plc reports beneficial ownership of 6,938,984 shares, representing 10.0% of the class.

Who within Janus Henderson signed the Schedule 13G/A for LNTH?

The filing is signed by Kristin Mariani, Head of North America Compliance, CCO, dated 08/14/2025.

Does Janus Henderson have sole voting power over these LNTH shares?

No. The filing reports 0 shares with sole voting power and 6,938,984 shares with shared voting power.

Are any subsidiaries identified as beneficial owners of LNTH shares?

Yes. The filing states that JHIUS may be deemed beneficial owner of 6,242,218 shares (9.0%) and names other indirect subsidiaries.

What type of filing is this and why was it submitted?

This is a Schedule 13G/A amendment filed under Rule 13d-1 to report beneficial ownership of LNTH common stock as required by the Exchange Act.

Is there a power of attorney included with the filing?

Yes. The filing includes a Power of Attorney executed Dec 9, 2022, authorizing named individuals to execute required filings.